Peat Bog Restoration Sphagnum peat moss is one of the most important ingredients for soilless media, howevermany questions have been raised abou t it. Where does it come from? How much is there? How long will it last? The following is the first of a three-part series that discusses Sphagnum peat formation, harvesting and restoration. Premier Horticulture has developed a restoration program that includes a policy and procedure for the opening and closing of peat bogs. The p rogram allows standardized management principles that are followed at all bog locations. The goal of this environmental management is to ensure the company’s continuance and secure peat moss for future generations. To better understand the ‘why and how’ of restoration, first let’s look at the Sphagnum plant. There are more than 335 species of Sphagnum around the world with about 16 species found in Canada. Approximately 5 species are dominant with most bogs limited to about three species. Sphagnum moss is a non-vascular plant (no roots) that grows in acidic water derived from precipitation. As it grows, it leaves behind dead portions, consisting of the cellulose and hemi-cellulose structure of the moss plant, to accumulate in the water, which we refer to as ‘peat moss’ (Figure 1). The unique structure holds water on the leaves, be tween leaves and stems and within the cellular structure. Inversely, air is found where water does not occupy. Sphagnum peat bogs are found in boreal regions of the northern and southern hemispheres. The combination of an acidic, low-nutrient watery environment and cool temperatures provide ideal conditions for sphagnum moss to grow. The cool temperatures and the absence of oxygen preserve the fibrous, organic layers of peat moss. In Canada, peat bogs, as seen in Figure 2, coverapproximately 111 million hectares (274 million acres) or about 12% of the total land area. In Quebec, peat moss harvesting began in the Bas St-Laurent region around 1933. For many years peat moss was harvested in block-cut sections with hand tools. In 1967, harvesting methods at Premier Horticulture changed to mechanical vacuum-harvesters, which has become the standard in Canada today. This is important to mention since h arvest methods have an impact on how peatlands are restored. In our next issue of Premier Press we will discuss harvesting and its relation to restoration. Since 1991, the Canadian Sphag num peat moss industry has funded research with the University of Laval in Quebec to study peat bogs and develop ways to restore peat lands. All producers agree that restoration is essential to maintain this valuable resource for future generations.
Peat Bog RestorationSphagnum peat moss is one of the most important ingredients for soilless media, howevermany questions have been raised about it. Where does it come from? How much is there?How long will it last? The following is the first of a three-part series that discussesSphagnum peat formation, harvesting and restoration.
Premier Horticulture has developed a restoration program that includes a policy and procedure for the opening and closing of peat bogs. The program allows standardizedmanagement principles that are followed at all bog locations. The goal of this
environmental management is to ensure the company’s continuance and secure peat moss for futuregenerations.
To better understand the ‘why and how’ of restoration, first let’s look at the Sphagnum plant. Thereare more than 335 species of Sphagnum around the world with about 16 species found in Canada.Approximately 5 species are dominant with most bogs limited to about three species. Sphagnummoss is a non-vascular plant (no roots) that grows in acidic water derived from precipitation. As itgrows, it leaves behind dead portions, consisting of the cellulose and hemi-cellulose structure of themoss plant, to accumulate in the water, which we refer to as ‘peat moss’ (Figure 1). The uniquestructure holds water on the leaves, between leaves and stems and within the cellular structure.Inversely, air is found where water does not occupy.
Sphagnum peat bogs are found in boreal regions of the northern and southernhemispheres. The combination of an acidic, low-nutrient watery environmentand cool temperatures provide ideal conditions for sphagnum moss to grow.The cool temperatures and the absence of oxygen preserve the fibrous,organic layers of peat moss. In Canada, peat bogs, as seen in Figure 2, cover approximately 111 million hectares (274 million acres) or about 12% of thetotal land area.
In Quebec, peat moss harvesting began in the Bas St-Laurent region around 1933. For many years peat moss was harvested in block-cut sections with hand tools. In 1967, harvesting methods atPremier Horticulture changed to mechanical vacuum-harvesters, which has become the standard in
Canada today. This is important to mention since harvest methods have an impact on how peatlandsare restored.
In our next issue of Premier Press we will discuss harvesting and its relation to restoration. Since1991, the Canadian Sphagnum peat moss industry has funded research with the University of Lavalin Quebec to study peat bogs and develop ways to restore peat lands. All producers agree thatrestoration is essential to maintain this valuable resource for future generations.
Harvesting Peatn the last issue of Premier Press, we discussed the formation and general characteristics of Sphagnum peat moss and peat bogs. This second part of the three-part series will discuss harvesting
of Sphagnum peat moss.
Some Sphagnum peat bogs are forested while others are not.Depending upon its geological age, Sphagnum peat bogs may or maynot have higher plants growing on their surface. Higher plants
include Tamarack, Spruce and plants from the genera Ericacea(blueberry, cranberry, rhododendron, etc.). In all cases, harvestingSphagnum peat moss begins with diverting the water within the peat bog. This is done by digging a series of ditches within a section of the bog to channel the water and lower the water table. Maintainingthe proper level of water in the bog is important, since introductionof air will accelerate the decomposition of the lower vegetative peatlayers of the bog. Careful attention is necessary to maintain anoptimum level of water for management of the peat, however enough
water must be removed to allow equipment to operate on the bog surface without ‘sinking’.
Water management alone cantake up to one year. Once thewater table is lowered to amanageable level, equipment canenter the peat bog to prepare its
surface. If present, trees are cut and used to makeroadways within the bog, then large stumps andsmaller vegetation are removed. In years past, the
surface containing live Sphagnum moss was rototilled to loosen the surface and scraped off. Today,this layer is carefully removed for use at restoration sites. This live Sphagnum moss is harvested andused to propagate Sphagnum plants in peat bogs that are no longer harvested (this will be further
discussed in the third part of this series). Once the surface is rototilled to loosen the compacted layer,large tractors pull specialized harrows to comb the surface and ‘roll’ the loosened peat so sun and aircan dry the Sphagnum peat moss.
Once dried to the optimal level, the blonde to light brown fibrous Sphagnum peat moss is harvestedwith large vacuum harvesters. This equipment drives across the bog surface drawing the driedSphagnum peat moss into a large canister that holds approximately 1,800 ft3. It only takes 10minutes for a harvester with a 25 foot-wide suction path to fill its canister. After filling, the harvesterunloads the Sphagnum peat moss into large piles, which are later transported to the factory for screening, grading, quality monitoring and packaging.
The size and depth of a Sphagnum peat bog determines the number of years peat moss can beharvested. The upper layers of the peat bog possess blonde fibrous peat, which is the youngest peat,geologically speaking. As bog layers are harvested, the degree of decomposition and humificationincreases, as does the age of the Sphagnum peat moss. Older peats are darker in color and possessshorter fiber. Shallow bogs are harvested for up to 7-10 years. Some deep bogs may be in productionfor over 50 years. In most cases, the upper layers of fibrous peat moss are harvested for horticultural purposes leaving behind the short fiber, dark brown layers. These peatlands are sometimes claimedfor agriculture and forestry purposes. However, when local and regional biodiversity are desired,methods are used to restore peat bogs to functional ecosystems. These sites are restored to naturalSphagnum peat moss accumulation, indigenous plant material and wildlife. This will be discussed inthe next issue of Premier Press.
Before plantingKeeping your greenhouses free of insects, diseases, algae and weeds is a good way to prevent themfrom becoming a problem. Before placing crops in your greenhouses, you should implement goodsanitation practices.
Sanitizing Structures & Equipment:
Disease organisms and algae are always present in a greenhouse. Many fungal and bacterial diseaseorganisms produce resting structures that can survive for several years. These pathogens are present
in dust and in used media on benches, floors, walkways, irrigation devices, re-used pots, labels, etc.Algae can be present on floors, benches, some irrigation devices, evaporative cooling pads, glazingand in irrigation water.
To sanitize the greenhouse, start by removing plant and media debris from floors, walkways and benches. Sweep and discard media that falls on the floor near a mixing machine, flat filler or potting bench, as it can easily be contaminated with pathogens from the floor.
Next, disinfect benches, irrigation devices, carts, floors, walkways, glazing and evaporative cooling pads with quaternary ammonium chloride salts (Q-salts) or bleach. If the irrigation water is asignificant source of algae, such as pond water, treat it with bromine, chlorination, an ozone
generator or hydrogen dioxide (Zero-tol). These treatments should also keep mist and drip lines freeof algae. If not, increase the rate of hydrogen peroxide or chlorine; allow the material to remain inthe water system for 24 hours, then flush the lines.
Re-using pots:
It is best not to re-use pots, but it inevitably happens.Start by removing all growing medium from pots, flats,tags, etc. Then soak them in Q-salts solution for 10 minutesor a 10% bleach solution for 30 minutes. Rinse the potswith water. This should kill most pathogens, but it does notnecessarily kill weed seed. The growing medium needs to be removed, as it can tie-up the active ingredient in both
chemicals, making them ineffective. Keep in mind theactivity of a bleach solution is reduced by 50% every
4 hours and should be recharged every 2 hours.
Weeds:
Remove all weeds inside the greenhouse as well as any weeds outside near the vents, doors or fans.Weeds can harbor fungal, bacterial and viral diseases as well as insects that transmit these diseases.Remove dead weeds as they might have seed heads or resting spores from fungal and bacterial pathogens. Place the weeds in garbage bags, so insects or weed seed do not disseminate in thegreenhouse. If there are a large number of weeds under the bench, they can be sprayed with postemergent herbicides such as Clethodim, Diquat, Glufosinate, Glyphosate or Pelargonic Acid. It
is best to apply them when there are no plants in the houses. Check the label for rates and for anygreenhouse application restrictions.
Compare the CostsIs it cheaper to make your own growing medium or to buy pre-made growing medium? To answer this question lets take a look at an example. The price for raw goods varies throughout the US andCanada, so lets see what it would cost to produce 560 yd3 (the equivalent of three truckloads of 3.8ft3 PRO-MIX) of a peat-perlite-vermiculite growing medium in central Texas. All prices areexpressed in US dollars.
Equipment:
To make this growing medium, a greenhouse operation would have to purchase a bale fluffer to fluff
the peat moss, a two-yard soil mixer and a conveyer to carry the peat to the soil mixer. The cost isapproximately $15,600. Assuming a ten-year depreciation period, the annual cost will be $1560 or $2.79/yd3 of growing medium. This does not include equipment maintenance.
Ingredients:
The ingredients are generally the largest expense. In this example, the growing medium contains70% peat, 15% perlite, 15% vermiculite, dolomitic limestone, wetting agent, starter macronutrientfertilizers and micronutrient fertilizer. The quantities and prices of each ingredient are in listed in
Table 1.
There is also yield loss when mixing these ingredients together. For example, peat will fill in thespaces between the perlite and vermiculite. Typically there is a 15-30% loss in yield. In our examplewe will assume a 15% yield loss, which means 15% more media, or 84 cubic yards, will need to be produced. This will increase the cost of each yard of growing medium by 15% (See Table 1).
Labor:Whom should make the growing medium? Often the owner, manager or grower does the job. Theyare the most qualified to do it. Unfortunately, this person is taken away from important growing or management decisions. They are also the highest paid, which increases the cost of producing thegrowing medium. Instead, a lower paid employee might be making the growing medium. This willreduce the cost of making the growing medium, but how reliable is this employee? For the sake of argument, lets say it will take one person, one hour to make two yards of mix and this person is paid$6.00 plus $1.50 for workers compensation, etc. ($7.50 per hour). This would add $3.75 per yard of mix (Table 1).
Almost all growing media manufacturers test their products for pH, soluble salts (EC), wettability,moisture content, etc. This ensures that their products conform to quality standards before they areshipped. If you make your own growing medium, test the pH and EC of each batch to check for certain blending errors. Purchase pH and EC meters that are reliable and calibrate them frequently.The cost for the equipment and calibration solutions is $0.05-0.10/yd3 and labor for processing thesamples is about $1.00/ yd3.
Total Bill:
The total cost per yard of mix is around $49.42 ($48.32 + $1.10 for testing), while a yard of PRO-MIX 'BX' is about $50.20. You only save a little money by mixing your own growing medium,however there are hidden costs such as dry storage space for fertilizers and lime, electricity, space toset up equipment, increased time placing orders, etc. Don’t forget about equipment breakdown, laborshortage and batch inconsistencies. If the growing medium is made improperly, crop quality suffers.We have frequently heard of a grower forgetting to add the limestone to the geranium mix. The pHof the mix is too low, micronutrient toxicities occur, a lot of time is spent trying to correct it, cropvalue is reduced and they end up losing money. There goes several years’ worth of savings!
Reputable growing media manufacturers test their products to make sure they are produced withintheir quality control guidelines. If they make a mistake, they will stand behind their product with
technical support and quality guarantees. There is some recourse for the customer. However, if thegrower produces the growing medium, there is no recourse. The choice is yours!
